Trifocal lens



P. ECKLEY TRIFOCAL LENS J1me13, 1930.

Original ,Filed May 6, 1925 MMW INVENTOR.

59w [CA/15K BY W {Q ATTORNEY Patented .Iu'ne 3, 1930 PATENT OFFICE PAUL EOKLEY, OJ! WALNUT CREEK, CALIB'OBNLA.

TBII'OOAL LENS Original application filed May 6, 1925, Serial No. 28,348. Divided and this application filed November 14, 1927. Serial No. 233,208. 4

This invention relates to improvements in lenses, and has particular reference to an improved construction of lens of the tri-focal or multi-focal type. The prime object of the present invention is to provide an improved construction of lens of the used type which embodies a plurality of foci to satisfactorily correct the vision of the wearer for near, in-

' termediate, and distance vision.

A preferred embodiment of the invention is disclosed in the accompanying drawing, and the object of this embodiment is to provide a lens having three field-a distance field, an intermediate field, and a reading field, the

intermediate field being constricted in width to about 1 mm. or less, so that its purpose is simply to act as'a shock-absorbing medium to the eye to prevent sudden transition from the distance field to the stronger reading field. A still further object of the invention is the provision of aliens consisting, of ground sections'fused together and arranged with respect to each other, whereby a lens may be further treated by a simple grinding and polishing operation and its manufacture quickly completed. Still another'object of the invention is the provision of a lens :inade up of a plurality of sections different indices of refraction and dioptric curvatures, said sections being fused together and properlyground to provide fields of vision wherein the lines of joinder between the fields are of uniform thickness and without shoulders or projections which would ordinarily cause zones of spherical or chromatic aberrations.

A still further objectof the inventionis to provide a device which is strong and durable inits construction, inexpensive to'manufacture, which is efiicient in its operation and adequately performs the services desired of it.

.A cross reference required by the law is hereby made to my co-pending application for a tri-focal optical lens, filed on May 6, 1925, and bearing the SerialNo'. 28,348, now

Patent No. 1,654,641, patented January 3,

1928, this application being a divisional application of thesame.

With the above numerated objects and many others in view, which will more readily appear as the nature of the invention is better understood, the same consists in the novel construction, combinatlon, and arrangement of parts which will hereinafter be more fully preferred embodiment of the invention is shown in the accompanying drawings in which:

Figure 1 is a view of one form of the blank used in the formation of my lens showing the difi'erent glasses fused together, from which glasses the tri-focal lenses are cut;

Figure 2 is a sectional view taken substantially along the line 22 of Figure 1, indicating the base glass and the inserted lens slightly separated to indicate certain features in the manner of manufacture;

Figure 3 is a view ,of one of the completedlenses formed from the blank shown in Figure 1 Figure 4 is a sectional view taken substantially along the line 4-4 of Figure 3;

Figure 5 is a sectional view similar to Figure 2, showing the sections of the lens sli ht- 1y separated to indicate the manner in 'w ich they are fused together;

Figure 6 is a section tliru the fuse lenses to show a manner of manufacture in which the glass insert bends downwardly at its edges and fuse; and

Figures 7, 8, 9, and 10 are views similar to Figures 1, 5, 3 and 4 respectively, but showing a slightly modified and preferred form of my invention. r a

Referring to the accompanying drawings, wherein similar reference characters designate similar parts thruout, the various figures described aboveadequately illustrate my invention, and the following detailed description is commensurate withth'e above mentioned drawings in enabling an artist to construct and assemble the constituent parts of the same. I

In the above mentioned drawin the ref- I erence numeral 1 indicates a blank om which I the tri-focal lens is'formed This blank comprises a base lens 2 whlch 1s preferably lens wil part of which is ground for one vision, but which has an outer annular rim 4, is suitable for an intermediate vision. This insertv lens may be formed in any suitable manner and of any suitable material, yet'it is preferable to form the same of flint glass, barium, or in fact any glass which has a high index of refraction, such as flint for example.

The insert lens 3 with the integral rim 4 is inserted on the preformed surfaces 6 and 7 in any of the well known manners, such as fusing. The insert may be fused in the manner shown in Figure 5. The outside edges 9 bend down and fuse into the surface 10 of the base member. Having formed a blank, as shown in Figure 1, this is preferably cut on one of its diameters, for instance the line 22. This forms two lens blanks as indicated by the dotted line 11 of Figure 1 which are cut and ground to form lenses as indicated in Figure 3. In this finished lens, the upper portion 12 of crown glass is used for distance vision, while the lower portion or sector 13 is used for the near or reading vision, and the partially annular section 14 forms the intermediate vision.

The manner of grinding the surface and of fusing the different types of glass are well known to those skilled in the trade and are not here described.

In Figures 7, 8, 9, and 10,-"I have shown a preferred embodiment of my invention. The ase lens 2' of crown glass i preferably ground as above described. T ggcentral insert 3 of flint glass, barium glass,- or the like is formed so that the annularring is of ver restricted width. The width is merel su ficient to' rovide a shock absorber to t e eye when the ocus on the retina is chan ed to ac-' commodate the diiferent local len s of the lenses. The width of the rim on t e insert is approximately 1 mm. but may be more or less as is desired. The intermediate vision is so narrow as toprevent the eye from seeing clearly thru the same, and it does not function to aid the eye in perceivin objects. As stated above, it merelfy; is provi ed to prevent sudden transition om a lens of one focal length to a lens of another focal length.

The manner of cutting the blank and formmg lenses from the same in a finished condition is the same as described above, and a reiteration of this description is not believed to be necessa From the foregoin it is thought that t e construction, use, an many advent of the herein described tri-focal be apparent without further description. I am aware that some. chan es may be made in the general arrangement and combination of the several parts, as well as in the details of construction thereof without departing from the scope of the present invention as set forth in the foregoing specification, and as defined in the following claims. Hence, I do not limit my invention to the exact arrangement and combination of the said devices and parts as described in the said specification, nor do I confine myself to the exact details of the construction of the said parts as illustrated in the accom anying drawing.

Having describe my invention, what I claim and desire to secure by Letters Patent 1. The method of making a glass lens which comprises forming a depression in a base glass of a certain index of refraction, insertmg a glass of another index of refraction in said depression, said insert having an annular junction surface for cooperation with an annular junction surface formed around the periphery of the'depression in the base glass to provide an area of intermediate focal length between the base glass and'the insert, permanently securing said glasses together ilmd finally forming and shaping a finished ens.

2. The method of making a glass lens which comprises forming a depression in a base glass of a certain index of refraction, said depression having an annular junction surface therearound forming a second glass of an other index of refraction so as to have a central portion of one focal length and a comparatively narrow annual, peripheral portion of another focal length, for cooperation with the annular junction surface of the base glass inserting said central portion in said depression, fusing said glasses together and finally f,qrmingand completin a lens whereby the same Wlll have areas 0 three different and distinct focal legths thru the base .glass, the insert, and peri hery of the insert 3. The metho of making a lens which comprises forming in a base glass a depression of a known curvature, forming on the riphery of this depression a narrow annu ar ring of a different curvature, placing an insert therein, said insert having a central portion to conform to the de ression, and-a narrow annular rim to con orm to the annular ring in the base glass, and fusing said base glass and insert together.

4. The method of making a tri-focal lens which comprises forming in a circular base glass a depression of a known curvature,

orming on the periphery of this depression a narrow annular ring of a different curvaan annular ring of a. different curvature forming on said insert an annular rim which has a curvature to conform to the annular ring on the base glass, placing said insert in said depression, fusing said insert to said base glass, cutting said base glass and fused insert transversely, and cutting and grinding each section to form a complete lens.

6. The method of making a tri-focal lens which comprises forming in a base glass a depression of a known curvature, forming on the eriphery of this depression an annular ring 0 .a difi'erent curvature, formin an insert having a central portion, whic has a curvature to match the curvature of said depression, forming on said insert an annular rim which has a curvature to conform to the annular ring on the .base glass, placin said insert in said depression, fusing sai insert to said base glass, cutting said base glass and fused insert transversely on the diameter thereof, and cutting and grinding each half section-to form a complete lens. In testimony whereof I aflix my signature. PAUL ECKLEY. 

